Hair straightener



FIG. 1 is a rear, right side and top perspective view of a hair straightener, showing my new design;

FIG. 2 is a front elevation view thereof.

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a left side, top and front perspective view thereof, shown in an open position of use; and,

FIG. 9 is a right side elevation view of FIG. 8 . 

CLAIM The ornamental design for a hair straightener, as shown and described. 